1. Field of the Invention
This invention relates generally to stripping, that is, removal of volatile organic compounds from contaminated surface and ground water and more particularly is directed to a method and apparatus utilizing a vertical tower in which the contaminated water is introduced in a fine spray and trickles down on a three-dimensional latticework while in contact with a high energy stream of air to remove the volatile contaminants which then escape through the upper open end of the tower. For ground water treatment, the well is equipped with an adjustable depth skimming chamber enabling controlled selection of upper levels of the aquifer for removal and delivery to the tower.
2. Description of the Prior Art
In stripping towers heretofore in use, air is blown into the tower through an elbow positioned to open in a downward direction to prevent the water, which is moving downwardly around the elbow, from entering the latter. The flow of incoming air must then reverse itself and pass upwardly around the elbow which forms a formidable restriction to the air flow and consequently substantially reduces the efficiency of the tower. This restriction to air flow was thought to be somewhat offset by using towers of greater diameter, as large as 30 to 36 inches. In these towers the ratio of air to water has been as high as 400 to 1 which translates into excessive cost for electric power to supply this air. In addition to cost, an example of the results of this inefficiency is the failure of attempts to remove dissolved acetone from water.
In purifying the aquifer of volatile organic compounds it is desirable to remove the liquid organic compounds which float on the ground water as well as treat the upper levels of the aquifer in which the dissolved organic compounds are higher in concentration. The well screen presently used and sunk into the aquifer to obtain the water for the towers, has horizontal slits in its wall spaced along the length thereof serving as perforations through which water passes and fills the well screen to the level of the ground water. As the water is pumped from the well for stripping, the water is replaced by passing through the slits in a haphazard manner at all levels. There, therefore, is a need for a device capable of controlling the level at which water is removed from the aquifer and particularly of skimming the upper levels.
When an oil or gasoline spill occurs, it is just a matter of time before the contamination spreads and seeps into the portion of the aquifer supplying the drinking water. It is, therefore, imperative that cleanup be commenced immediately at the site of the spill where the floating contaminants can be recovered and removed and the dissolved contaminants stripped from the water which is then returned to the ground. Strategic location of the drain field where the purified water is returned with respect to the location of the recovery wells can materially reduce the spreading of the spill. Thus, there is also a need for the equipment to be relatively easy to transport, set up on site, disassemble and relocate.
In areas such as south Florida where the aquifer supplies the drinking water, a compelling need exists to promptly, effectively and economically remove any volatile organic compounds, such as gasoline and oil, which have spilled and drained into the ground water.